When the COVID-19 virus first enters the host respiratory tract, infection is initiated via the binding of the spike protein with angiotensin-converting enzyme 2 (ACE2) receptors, with the subsequent utilization of the transmembrane protease-serine 2 (TMPRSS2) to enter host cells; the virus then hijacks the host cellular machinery for viral RNA replication and protein production [43]. This evidence concerns the gene TMPRSS2 and COVID-19.